GNetWatch is a free open source Java application that offers real-time graphical monitoring and analysis of network performance through SNMP and ICMP. To get an instant view of the network state, data are collected, stored and displayed every few seconds. Two traffic generation modules are available. The former can flood UDP packets of any size (jumbo frames for instance) and tagged with any DiffServ/ToS flag for QoS and class of services testing. The latter can generate a huge quantity of parallel requests to any HTTP(s) server, for web applications load testing. To automatically discover new hosts, GNetWatch can make use of Ethereal/WireShark and later invoke NMap to get informations about the remote systems. Note that IPv6 and SNMPv3 are fully supported by GNetWatch.